The New York Rapid-transit Subway

46 PARSONS ON NEW YORK RAPID-TRANSIT SUBWAY. [Minutes of Table IX. Kind. 1st Crack. Ultimate. Load. Compression. Load. Per Square Inch. Untouched 65,000 Inch. 0'049 69,320 1,925 Retempered 24 hours 62,000 0-041 70,800 1,970 » 48 „ 32,000 0-041 33,020 914 As has been shown, the underground portions of the railway were built partly by tunnelling and partly by open excavation. Wherever streets were wide and traffic light, great latitude was given the contractor in the way of opening and obstructing streets. Where, however, the streets were narrow, important, or congested with surface traffic that could not be diverted, the work of excavation and construction was carried on under a temporary timbered surface. The most extensive work of this character was done in lower Broadway. The first step after removing the paving at night was to lay in each of three longitudinal trenches a pair of 20-inch 80-lb. beams. Transverse to the street, and resting on these beams and at the sides on either the vault-walls or a 10-inch by 10-inch timber cap, were laid 8-inch beams at every 10 feet. On top of these beams was the wearing surface of 6-inch yellow-pine planks. Under this cover excavation proceeded, the main beams being supported at 15-foot intervals by three pairs of 12-inch by 12-inch pine posts. Suspended from the 20-inch beams were cross timbers 10 inches by 12 inches in section, one beneath each tramway-yoke, i.e., 5 feet apart, to carry the yokes and tramway. The vault-walls along the curbs acted as convenient retaining-walls, but where such walls were not present the earth was held by vertical sheeting and cross braces. Cost. The total cost of building the subway, with its 25'7 miles of route and 76'5 miles of main track, was about 350,000,000, exclusive of equipment, which, for the power-plant, rolling stock, signals and all other appurtenances, cost about $25,000,000 more, and exclusive of interest during construction and of easements. It must be remembered that the cost of construction covers a considerable mileage of elevated railway, which is much cheaper than underground construction. The cost of constructing the subway portions ranged from about $1,000,000 to $1,250,000 per mile of each track. The main contracts were taken by the Rapid Transit Subway Construction